Great review! I have an SG Approach and have started looking for a larger bag for a 3 day trip (trying to decide between the new R3 or the Sky Archer).
One thing I wanted to mention though is Justin didn't like the gun bearer. In the pictures it looks like the tail end is behind him blowing in the breeze making it impossible to grab.
You can thread it down under the webbing on the front of the shoulder strap and it sits right at breast pocket level, and I found it stays there pretty much all day. I found it very easy to pull the rifle out in less than 5 seconds or so with minimal contorting to reach anything - it takes a little bit to get the rifle in there and it is impossible to do it yourself while wearing the pack, but removal is quick if you have the tail tucked in the shoulder strap. This video shows what I am talking about, you can go to the 5:20 mark to see what I am describing:
Stone Glacier Weapon Sling - YouTube